The World of GIS Hydro ‘98 David R. Maidment University of Texas at Austin Presented by:
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Transcript of The World of GIS Hydro ‘98 David R. Maidment University of Texas at Austin Presented by:
The World of GIS Hydro ‘98
David R. MaidmentUniversity of Texas at Austin
Presented by:
GIS Hydrologic Modeling
Environmental description Process representation
Data
Input
Model
Results
Synthesis of GIS and Modeling
Linking Data and Models
Integrated Spatial Database GIS Hydro ‘98 Models
Watershed Characterization
Runoff & Routing
Hydraulics
Water Quality
Atmosphere & Soil Water
Traditionalapproach
SpatialHydrology
ProcessRepresentation
EnvironmentalDescription
Process-basedModeling
Map-basedModeling
Hydrologic Modeling
Users
Hydrologicsimulation
Timeseriesdata
Spatialhydrologicmodel
Spatialdata
RealWorld
Spatial Hydrologic Modeling Concept
t
t
t
I Q
t
Continuous time hourly, daily
Steady state mean annual
Seasonal monthly
Single event
Dealing with Time Variation
Two tasks:
I. Environmental descriptionusing a map
II. Process representationusing equations
Modeling Procedure
Environmentaldescription
Processrepresentation
1. Study design 2. Terrain analysis 3. Land surface description 4. Subsurface description 5. Hydrologic data representation 6. Soil water balance 7. Water flow 8. Constituent transport 9. Impact of water utilization 10. Presentation of results
Ten Step Procedure for Modeling
Objectives of the study? Range and subdivision of the spatial domain? Duration and subdivision of the time horizon? Variables to be computed?
Step 1. Study Design
Computationaleffort ~ LMN
LMN < 10,000,000for execution within ArcView
Number of:Spatial units = LVariables computed = MTime intervals = N
Time Variables
Space
N
M
L
Space, Time, and Process Variables
Mean annual flow andtransport on a raster grid
Time
Variables
SpaceN=1
M
L
Time-Averaged Modeling
LandCharacterization
(Land use,Soils,
Climate,Terrain)
Water Characterization(water yield, flooding, groundwater, pollution, sediment)
Relationships between land type and water characteristics
Land and Water Interaction
LandCharacterization
(Land use,Soils,
Climate,Terrain)
Non Point Source Pollution(mean annual flowsand pollutant loads)
Adapt Water to the Land System
Water Characterization(water yield, flooding, pollution, sediment)
LandCharacterization
(Land use,Soils,
Climate,Terrain)
Water Characterization(water yield, flooding, pollution, sediment)
CRWR-PrePro(GIS Preprocessorfor HEC-HMS floodhydrograph simulation)
Adapt Land to the Water System
CRWR-PrePro: HMS Preprocessor
Geographic Data Schematic Diagram
Increasing Scale Increasing Complexity
Digital Elevation Model (DEM)
Vector representation as points, lines and areas Raster representation on a grid of DEM cells
Vector
Raster
Outlet Stream Watershed
Raster-Vector Equivalence
+ =
Take a mapped stream network and a DEM Make a grid of the streams Raise the off-stream DEM cells by an arbitrary elevation increment Produces "burned in" DEM streams = mapped streams
“Burning In” the Streams
Begin with an elevation grid Flow in direction of steepest descent
Eight-Direction Pour Point Model
78 72 69 71 58 49
74 67 56 49 46 50
69 53 44 37 38 48
12
21
22
11
16
31
12
19
24
53
61
58 55
47
34
68
74
64
Elevation Flow direction grid
Flow Direction Grid
Flow Direction
Water flows to one of its neighbor cells according to the direction of the steepest descent.
Flow direction takes one out of eight possible values.
Flow direction gridImplied network
between cell centers
Grid Network
0 0 0 0 0 0
0 1 1 2 2 00 3 7 5 4 0
71
20
3524
0
10
1
20
0 0
04
00
0
Number ofupstream cells
Classification of flow accumulation
Number of cells > 6 = stream0 cells = watershed boundary
1 1 2 2
3 7 5 4
7
1
20
35
24
1
1
2 4
Flow Accumulation Grid
Flow Accumulation
Flow accumulation is an indirect way of measuring drainage areas (in units of grid cells).
Types of Outlets and Nodes
Stream junction node
Stream headwater node
System outlet node
User-defined nodeSub-basin
Stream
Stream Segmentation
Stream segments (links) are the sections of a stream channel connecting two successive junctions, a junction and an outlet, or a junction and the drainage divide.
Watershed Delineation
The drainage area of each stream segment is delineated.
What DEM cell size to use? Cell size = Region area / 1,000,000
What size watershed to delineate? Watershed > 1000 cells
Thousand-Million Rule
Cell Size WatershedArea (km2)
TypicalApplication
1” (~ 30 m) 3” (~ 100 m)15” (~ 500 m)30” (~ 1 km) 3’ (~ 5 km) 5’ (~ 10km)
540
10004000
150,000400,000
Urban watershedsRural watershedsRiver basins, StatesNationsContinentalGlobal
Application of Digital Elevation Models
Raster to Vector Conversion
Streams and watersheds are converted from raster to vector format.
Dissolving Spurious Polygons
Cells connected to the main watershed polygon through a corner are defined as a separate polygon (spurious polygon).
These polygons are dissolved into the main polygon.
Watershed Parameters
Flow length upstream and downstream
AverageCurve Number
Slope and length of the longest flow-
path
Identification of the longest flow-path
Lag-timeSCS Unit
Hydrograph
distance downstream to outlet
Flow-Length Function in ArcView
distance to upstream divide
Flow Length Downstream to the
Watershed Outlet
Flow Length Upstream to the Watershed
Divide
Longest Flow-PathTotal flow length = upstream length + downstream length
V21
V11
V41
V31
V61
V51
V32
V12
V22
V42
V52
V62
V23
V13
V33
V53
V43
V24
V16V15V14
V63
V34
V44
V54
V64
V25
V35
V45
V55
V65
V26
V36
V46
V56
V66
Velocity magnitude Velocity direction
V = aSb
S = slopea,b = land cover coefficients
Velocity Field
time to outlet (weighted flow length)
Time = Distance x1
Velocity
Flow Time Computation
Isolation of a Sub-System
Connection to HEC-HMS
HMS Schematic Parameter Transfer
HMS Basin File
Ferdi’s code
Upper Mississippi Flood Study
Streams and Subwatersheds
162 subwatershedseach with a USGS gage at the outletdefined using 15” (500m) DEM
Rivers definedby EPA RiverReach File 1 (RF1)
CRWR-Prepro Schematic Network
Inlets
Mississippi River
Missouri River
Outlet (Mississippi R.at Thebes, Ill)
HEC-Hydrologic Modeling System
HMS Basin file
CRWR-PrePro HEC-HMS Model Schematic
LandCharacterization
(Land use,Soils,
Climate,Terrain)
Non Point Source Pollution(mean annual flowsand pollutant loads)
Adapt Water to the Land System
Water Characterization(water yield, flooding, pollution, sediment)
Land-WaterConnection
TransformCoefficient
Water yield Runoff coefficient, C
Flood runoff SCS Curve Number, CN
Groundwater Recharge rate (mm/yr)
Water quality Expected Mean Concentration(mg/l)
Sediment yield Erosion rate (tons/ha-yr)
Possible Land-Water Transform Coefficients
Water
Land
Map-Based Surface Water Runoff
Runoff, Q (mm/yr)
Precipitation, P(mm/yr)
Accumulated Runoff (cfs)
P
Q
Runoff CoefficientC = Q/P
Water Quality: Pollution Loading Module
DEMPrecip. Runoff
LandUse
EMC Table
ConcentrationLoad
AccumulatedLoad
Load [Mass/Time] = Runoff [Vol/Time] x Concentration [Mass/Vol]
Expected Mean Concentration
Constituent Resident. Comm. Indust. Transp. Agric. Range UndevelTotal Nitrogen (mg/l) 1.82 1.34 1.26 1.86 4.40 0.70 1.50Total Phosphorus (mg/l) 0.57 0.32 0.28 0.22 1.30 <0.01 0.12Oil and Grease (mg/l) 1.7 9.0 3.0 0.4Copper (ug/l) 15.0 14.5 15.0 11.0 1.5 <10Chromium (ug/l) 2.1 10.0 7.0 3.0 <10 7.5Zinc (ug/l) 80 180 245 60 141 16 6
Land Use
EMC
Table derived from USGSwater quality monitoring sites
Total Constituent Loads
Input for WaterQuality Model
Water Quality: Land Surface -Water Body Connection
Bay Water Quality
Flood Hydraulics
Given the flood discharge (HEC-HMS), what is the water surface elevation (HEC-RAS, River Analysis System)
How to draw flood plain maps?
HEC-RAS
AVRAS
Cross-sectionmapping
Flood Hydraulics: Stream Geometry Data
Determine cross-section elevations from TIN terrain data HEC-RAS pre- and post-processing using avRAS (ArcView) or
HEC AMLs (Arc/Info) Visualize floodplain TINs with ArcView’s 3D Analyst extension
asfloodrises
Hydraulics: RAS Stream Geometry Data
Digital orthophoto serves as a base map upon which to digitize the stream
Avenue scripts create an ArcView cross-section table from the HEC-RAS output text file
Link cross-section table records to cross-section locations on the digitized stream
GIS - River Analysis System (AVRAS)
Pre Processor(Avenue)
GIS
GIS RAS Import
RAS 2.0
GIS RAS Export
Post Processor(Avenue)
GIS
Hydraulic Input
Dean Djokic& Zichuan Ye
(ESRI)
Stream Bed Shape in ArcView
Cross-sections
Flood Plain in HEC-RAS
Floodplain in ArcView
Floodplain in ArcView 3-D Analyst
Spatial Hydrology Virtual Campus Courses
ESRI Virtual Campus course on Spatial Hydrology (http://campus.esri.com/campus/home/home.cfm)
University of Texas GIS in Water Resources online course during Fall 1998 (limited enrollment) (http://www.ce.utexas.edu/prof/maidment)
DHI: Hydraulic & Water Resources Engineering
MIKE SHEMIKE SHEMIKE BASINMIKE BASIN
MIKE 11MIKE 11MOUSEMOUSE
DHI Models
Pipe Networks
River Basin Networks 1-D River Modeling
Hydrologic Modeling
Danish Hydraulic Institute
BYU: Surface and Groundwater Flow
Integrates digital terrain models with standard
runoff models such as HEC-1, TR-20, TR-55.
Subsurface Representation and Model Interface for Groundwater Simulation: MODFLOW, MT3D, MODPATH, SEEP2D, and FEMWATER.
Two-Dimensional Surface Water Model Interface for RMA2, RMA4, RMA10, HIVEL2D, FLO2DH (FESWMS), ADCIRC, CGWAVE, WSPRO, SED2D-WES, and DAMBRK.
Brigham Young University
EPA: Water Quality
TOXIROUTE
NPSM QUAL2E
US Environmental Protection Agency
ArcViewPreprocessor forWater Quality Models